diff options
| -rw-r--r-- | pm/HOWTO.hooks | 2 | ||||
| -rw-r--r-- | pm/functions.in | 26 |
2 files changed, 15 insertions, 13 deletions
diff --git a/pm/HOWTO.hooks b/pm/HOWTO.hooks index ad7d4a7..ce9e8c4 100644 --- a/pm/HOWTO.hooks +++ b/pm/HOWTO.hooks @@ -99,7 +99,7 @@ the hook. This will make the following convenience functions available: 2: spin_lock Wrapper around try_lock. Second parameter is the number of seconds to wait for the lock before giving up. If no second parameter - is passed, this function will wait forever. + is passed, this function will wait for 60 seconds. 3: release_lock Release a previously acquired lock. First parameter is the name of the lock. diff --git a/pm/functions.in b/pm/functions.in index 2c258e6..bd649db 100644 --- a/pm/functions.in +++ b/pm/functions.in @@ -22,13 +22,13 @@ is_set "${PM_DEBUG}" && set -x try_lock() { # $1 = file to use as lockfile - # $2 (optional) content to write to the lockfile, - # extra newline will be appended + local lock="${LOCKDIR}/${1##*/}" + # make sure the directory where the lockfile should be exists mkdir -p "${LOCKDIR}" - local lock="${LOCKDIR}/${1##*/}" - # we use noclobber to make sure there are no race conditions - (set -o noclobber; echo "${2}" > "${lock}") 2> /dev/null || return 1 + touch "${lock}" + exec 3<"${lock}" + flock -x -n 3 || return 1 return 0 } @@ -37,13 +37,15 @@ try_lock() spin_lock() { # $1 = lockfile - # $2 = optional timeout - local elapsed=0 - while ! try_lock $1; do - [ "x$2" != "x" ] && [ $(( $elapsed == $2 )) -ne 0 ] && return 1 - elapsed=$(($elapsed + 1)) - sleep 1; - done + # $2 = optional timeout (default is 60 secs) + local lock="${LOCKDIR}/${1##*/}" + local timeout="${2:-60}" + + mkdir -p "${LOCKDIR}" + touch "${lock}" + exec 3<"${lock}" + flock -x -w "${timeout}" 3 || return 1 + return 0 } # release the lock |